Problem: $ { \left[\begin{array}{rrr}{-1} & {3} & {4} \\ {2} & {0} & {2}\end{array}\right]+\left[\begin{array}{rrr}{-2} & {0} & {3} \\ {0} & {0} & {-1}\end{array}\right] = {?} } $
To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rrr}{-1}+{-2} & {3}+{0} & {4}+{3} \\ {2}+{0} & {0}+{0} & {2}+{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{-3} & {3} & {7} \\ {2} & {0} & {1}\end{array}\right]}$